Hello and welcome to Y.T.......I have three boys and had them all neutered around 6-8 months old......I was waiting because yorkies have a tendency to retain baby teeth so I wanted to have them extracted at the same time as when the neutering was done.....I didn't want them put under anesthesia twice......
As for a change in attitude I didn't notice any change what so ever. I even obtained a male at 18 months old....he wasn't neutered and he was a sweet heart. After his neutering he was still a sweet heart. ....The only thing I did notice was a lot less lifting, which was a definite benefit......
I'm sure everything will be ok to wait and do it when
you feel he's ready......
